Motor vehicles – With means for promoting safety of vehicle – its occupant or... – Responsive to sensing of acceleration – deceleration – or tilt...
Reexamination Certificate
2000-10-02
2001-11-13
Dickson, Paul N. (Department: 3618)
Motor vehicles
With means for promoting safety of vehicle, its occupant or...
Responsive to sensing of acceleration, deceleration, or tilt...
C280S735000, C701S045000
Reexamination Certificate
active
06315074
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention lies in the automotive technology field. The invention relates to a device and a method for triggering an occupant protection system in the event of a motor vehicle rollover. The expression “motor vehicle rollover” as used herein includes both a threatened motor vehicle rollover and a rollover that is actually taking place.
Occupant protection systems that can be activated in the event of a motor vehicle rollover include, for example, passive restraint systems such as, i.e., a head airbag, a side airbag, a seat belt pretensioning system, a seat belt clamping system, and/or an upwardly foldable rollover bar. Furthermore, occupant protection can also be enhanced by using systems that can be activated during and after an accident (post-crash systems). Such systems can include, for example, generating an emergency signal, opening the central locking, switching on the hazard warning system, and/or switching off the fuel pump.
German Patent DE 35 45 874 C1, corresponding to U.S. Pat. No. 4,715,468, discloses a device triggering an occupant protection system in the event of a motor vehicle tilting movement about a motor vehicle longitudinal axis. The device includes an inertia switch that is closed when there are vehicle accelerations in the vehicle's x- and y-planes above a specific acceleration value. When the threshold is exceeded, the device activates a rollover bar occupant protection system. Connected in parallel with the inertia switch is a series circuit made of inclination switches, which detect rolling movements of the motor vehicle, and suspension switches. The rollover bar is triggered whenever one of the inclination switches responds and one of the suspension switches signals rebounding of a motor vehicle rear wheel. However, in certain circumstances, for example, extreme cornering, there is the risk of an unnecessary, surprising, and, therefore, dangerous triggering of the occupant protection system. Correct, timely triggering of the occupant protection system is not ensured in all accident situations.
European Patent 0 430 813 B1 discloses an occupant protection system including a gyrometer and three accelerometers that determine the longitudinal, transverse, and vertical accelerations of the motor vehicle. The triggering device of the occupant protection system is activated either when the combined longitudinal and transverse accelerations exceed a prescribed threshold value, when the gyrometer output signal is situated above a specific threshold, or when the gyrometer output signal integrated over a prescribed time interval exceeds a specific threshold. The gyrometer output signal is, however, not referred to a fixed space coordinate system, and, therefore, does not permit a firm conclusion on the actual angle of inclination of the motor vehicle with reference to the horizontal plane. For the system, certain is difficulties are encountered for determining the triggering threshold value.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a device and a method for triggering a motor vehicle occupant protection system that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that permits reliable triggering of the occupant protection system in the case of a motor vehicle rollover.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a device for triggering an occupant protection system when a motor vehicle tilts about a motor vehicle longitudinal axis, including a rate-of-rotation sensor detecting a rate of motor vehicle rotation about a longitudinal axis of the motor vehicle and for generating a rotation output signal, an inclination sensor for detecting motor vehicle inclination and for generating an inclination output signal, and a triggering device for activating an occupant protection system based upon the rotation output signal and the inclination output signal, the triggering device connected to the rate-of-rotation sensor and the inclination sensor and configured to trigger an occupant protection system only when both the rate-of-rotation sensor outputs a signal indicating a rotary movement greater than or equal to a specific value, and the inclination sensor outputs a signal indicating a motor vehicle inclination angle greater than or equal to a given value.
Incipient vehicle rollovers can be sensed in good time using the rate-of-rotation sensor in conjunction with the inclination sensor. Specifically, an impending rollover can be detected very quickly because the rate of rotation measured by the rate-of-rotation sensor provides such a statement at a sufficiently early point in time. However, the occupant protection system is not triggered until the inclination sensor signals an (absolute) oblique position of the motor vehicle likely to cause an accident. The triggering of the occupant protection system can take place virtually without delay upon response of the inclination sensor because the rate-of-rotation sensor has already detected the incipient vehicle rollover. Therefore, the inclination sensor serves as a safing sensor. However, depending on the accident situation it is also possible for the inclination sensor to respond initially, resulting in the occupant protection system being immediately triggered when the rate-of-rotation sensor also responds.
Because two sensors based on different measuring principles are provided, the reliability of the occupant protection system can be greatly increased. For example, the rate-of-rotation sensor can be based on the measuring principle of using the Coriolis force, which acts on moving bodies in a rotating reference system. In contrast, the gravitational force of the earth is preferably utilized for the inclination sensor. As such, the inclination sensor can detect the inclination uniaxially about the vehicle longitudinal axis, or omnidirectionally in the vehicle plane.
The triggering signals generated by the rate-of-rotation sensor and inclination sensor are combined, as it were, in the form of an “AND” operation, such that the occupant protection system is ignited only when both conditions are fulfilled.
In accordance with another feature of the invention, the triggering device is configured to block activation of the occupant protection system when the inclination output signal indicates a tilted position of the motor vehicle lasting longer than a predetermined time interval even if the rotation output signal subsequently indicates a motor vehicle tilting movement about the motor vehicle longitudinal axis.
Because the inclination sensor indicates the absolute angular position of the vehicle, at least roughly, it is possible to is prevent triggering of the occupant protection system in the event of a tilting back of the motor vehicle from the vertical position of the vehicle, or a position on its roof, or a position on its side into the normal position. Specifically, if the occupant protection system should not have responded in the event of rollover of the motor vehicle for reasons of whatever sort, for example, because of an extremely slowed-down vehicle rollover, or because of a strong deliberate tilting (i.e., extreme jacking up in a workshop) with the ignition switched off, there is a risk that, should the motor vehicle be tilted back again into the normal position by the persons involved in the accident or by the recovery staff, the occupant protection system would be triggered. For example, the rollover bar could be erected suddenly. The feature inherently endangers the persons located at or in the vehicle. Such endangerment can be avoided by using the inclination sensor to block a triggering signal. The safety feature can be implemented in terms of circuitry in a simple way by blocking the occupant protection system from being triggered when the inclination sensor signal indicates that the motor vehicle has been in a tilted position over a lengthy period of time exceeding a prescribed threshold
Achhammer Günter
Glaser Telmo
Dickson Paul N.
Greenberg Laurence A.
Lerner Herbert L.
Siemens Aktiengesellschaft
Stemer Werner H.
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